Conventionally, sucrose (sugar) has been widely utilized as a sweetener in edible products such as food products, drugs and the like, since such sugar has a favorable sweetness and good body, and since this sucrose is also superior in terms of characteristics such as imparting of moisture retention, viscosity and the like. However, although sucrose has a favorable sweetness and good body, the sucrose has come to be avoided because it is a cause of obesity and tooth decay, and there is a trend toward an improved health and a reduction in caloric intake recently. Especially in the case of favorite foods such as beverages, confections and the like, there has been a progressive lowering of sugar content and caloric content. Accordingly, there has been a demand for a sweetener that has a favorable sweetness comparable to that of sucrose, and that also has a low caloric content, as a sweetener used in the manufacture of such favorite foods. Furthermore, this demand for reduced caloric content and favorable sweetness is not limited to the favorite foods, but also arises in regard to a table sweetener. Moreover, in general food products as well, there has been a desire for a light and moderate sweet taste.
In order to meet such demands of consumers, so-called “high-intensity sweeteners” have appeared as sweeteners used in place of sucrose. Since most of these sweeteners have a stronger sweetness than sucrose, these sweeteners also have the characteristics of “low-calorie sweeteners” that can impart sweetness comparable to that of sucrose when used in smaller amounts than sucrose. Examples of such high-intensity sweeteners include aspartame, potassium acesulfame, licorice extract, saccharin, sodium saccharin, sucralose, stevia extract, neotame and the like. However, there are few high-intensity sweeteners that have a favorable sweetness and body comparable to those of sucrose; most of these sweeteners have a peculiar bitter taste or astringent taste, and a lingering taste (aftertaste) in which the sweet taste tends to linger. In the past, therefore, there has been a demand for methods to ameliorate disagreeable tastes such as the abovementioned bitter taste, astringent taste or aftertaste.
Meanwhile, sclareolide ((3aR,5aS,9aS,9bR)-decahydro-3a,6,6,9a-tetramethylnaphtho[2,1-b]furan-2(1H)-one) is a natural norlabdane type terpenoid which is found (for example) in tobacco (Kaneko, H., Agr. Biol. Chem., 35 (9): 1461 (1971)). It is known that this sclareolide has a masking or enhancing action with respect to specified tastes (see U.S. Pat. No. 4,917,913, U.S. Pat. No. 4,960,603, U.S. Pat. No. 4,966,783 and U.S. Pat. No. 4,988,527). Furthermore, it is also known that sclareolide is used as a fragrance in cigarette tobacco (Japanese published un-examined patent application No. 60-123483), and as an additive for eliminating the bitter taste of coffee (U.S. Pat. No. 4,988,532). Moreover, it is also known that this substance has an effect in improving the aftertaste of aspartame (U.S. Pat. No. 4,999,207).
Meanwhile, 2-acetylpyrrole is known as a fragrance enhancing agent for tobacco (British Patent No. 1,248,313). Furthermore, in the Collection of Universally Known and Customary Technology issued by the Japanese Patent Office, this substance is cited as a fragrance that has a masking effect (Japanese Patent Office Gazette 11 (1999)-6 Collection of Universally Known and Customary Technology (Fragrances), Part 1, General Fragrances, issued Jan. 29, 1999).
However, when sclareolide is used along, the effect in improving the taste by suppressing the disagreeable taste of high-intensity sweeteners is insufficient; furthermore, in the case of 2-acetylpyrrole, no effect in suppressing the disagreeable taste of high-intensity sweeteners or improving the taste of sweeteners is known.